What NEC edition does Minnesota use for solar in 2026?

Minnesota has adopted NEC 2020 for solar PV installations. All systems must comply with NEC 2020 Article 690 including the residential 600V voltage limit (690.7), 125% conductor sizing with cold-climate temperature correction (690.8), and rapid shutdown for rooftop systems (690.12). The cold Minneapolis minimum temperature (-31°C) requires careful NEC 690.7 string voltage calculation — more modules may fit per string than in warm climates because cold temperatures increase Voc.

How does Xcel Energy Solar Rewards work in Minnesota?

Xcel Energy's Solar Rewards program is a performance-based incentive for residential and small commercial solar in Minnesota. Participants receive a per-kWh payment for all solar production — both self-consumed and exported. Solar Rewards is offered in addition to net metering (not a substitute). Payments vary by year of enrollment and system size. The program has waitlists during high-demand periods — check Xcel's website for current availability and payment rates.

Does Minnesota have net metering?

Yes. Minnesota PUC mandates net metering for all electric utilities. Residential systems up to 40 kW and commercial systems up to 1 MW are eligible. Excess credits accumulate at the retail rate and carry forward monthly. Annual excess credits are compensated at the retail rate — Minnesota is one of the more favorable states for annual excess treatment.

How does cold weather affect string voltage calculations for Minneapolis?

Minneapolis has an ASHRAE extreme minimum temperature of -31°C (-24°F). Per NEC 690.7, the temperature-corrected Voc uses the minimum temperature: correction factor = 1 + (-31 - 25) × (β_Voc / 100). For a module with β_Voc = -0.30%/°C: factor = 1 + (-56) × (-0.003) = 1.168. A module with Voc = 45V in Minneapolis would have a cold-corrected Voc of 45 × 1.168 = 52.6V per module. For a 600V residential system: max modules = 600 / 52.6 = 11.4 → 11 modules. Cold weather restricts the maximum string length.

What is the Made in Minnesota solar program?

Made in Minnesota (MiM) is a state incentive program for solar systems using modules manufactured in Minnesota or by MN-headquartered companies. The program provides performance-based incentives (per-kWh payments) for eligible systems. MiM incentives are higher than standard Solar Rewards rates for qualifying equipment. The program is administered by the Minnesota Department of Commerce — check current enrollment status and payment rates, as the program may have waitlists.

Minnesota Solar Compliance Guide 2026: NEC 2020, Xcel Energy Interconnection & SREC Programs

Minnesota’s solar market is concentrated in the Twin Cities metro area, where Xcel Energy’s Solar Rewards program and Minnesota’s favorable net metering treatment create strong economics. Cold-climate string voltage calculations are a key NEC compliance consideration — Minneapolis’s -31°C design minimum requires careful Voc calculation.

Minnesota Solar Snapshot

NEC Edition: 2020 | Primary Utility: Xcel Energy (Twin Cities), Great Plains Energy (southern MN), Minnesota Power (northern MN) | Net Metering: Mandatory for all utilities (retail rate, annual excess compensated) | State Programs: Solar Rewards, Made in Minnesota | Federal ITC: 30% residential / up to 50% commercial

NEC 2020 in Minnesota

Minnesota adopted NEC 2020 statewide. Cold-climate solar design requires special attention to NEC 690.7:

Cold-Climate String Voltage (NEC 690.7)

Minneapolis has one of the lowest ASHRAE minimum temperatures in the continental US:

City	ASHRAE T_min	Correction Factor (β_Voc = -0.30%/°C)
Minneapolis	-31°C	1.168
Duluth	-31°C	1.168
Rochester	-28°C	1.159
St. Paul	-31°C	1.168

Worked example — Minneapolis residential:

Module: Voc = 45.0V, β_Voc = -0.30%/°C, Residential 600V system

Correction factor = 1 + (-31 - 25) × (-0.003) = 1 + 0.168 = 1.168
Corrected Voc per module = 45.0 × 1.168 = 52.56V
Maximum modules = 600 ÷ 52.56 = 11.41 → 11 modules maximum
Verification: 45.0 × 11 × 1.168 = 577.7V ✓ (below 600V)

For commercial (1000V):

Maximum modules = 1000 ÷ 52.56 = 19.0 → 19 modules

Conductor Sizing — Minneapolis Climate

Minneapolis requires the opposite consideration from desert markets: conductors may be oversized to handle cold-temperature Voc, but the ampacity derating is minimal (cold air, no rooftop heat gain concern in winter):

Parameter	Value
ASHRAE max air temp	34°C
+ 22°C rooftop adder	+22°C
Effective conductor temp (summer)	56°C
THWN-2 (90°C) correction factor	0.76

Summer rooftop derating in Minneapolis (0.76) is less severe than Phoenix (0.65) but still significant.

Xcel Energy Interconnection and Solar Rewards

Xcel Energy is the primary utility for the Minneapolis-St. Paul metro (about 60% of Minnesota’s population):

Interconnection Process

System Size	Process	Timeline
Under 20 kW residential	Fast Track	10–20 business days
20 kW–2 MW	Level 1 study	45–90 days
Over 2 MW	Level 2 study	6–18 months

Solar Rewards Program

Xcel’s Solar Rewards provides per-kWh incentive payments:

System Size	Incentive Structure
Under 20 kW	Per-kWh payment for all production
20 kW–40 kW	Same structure, different rate tier

Solar Rewards payments are in addition to net metering credits — the system receives both the net metering credit (retail rate for exported kWh) and the Solar Rewards production payment (for all kWh generated).

Current rates: Check Xcel’s website for current Solar Rewards payment rates — rates vary by enrollment year and program capacity.

Solar Rewards Waitlist

Xcel’s Solar Rewards program has been oversubscribed in high-activity periods. Join the waitlist early — enrollment occurs on a first-come, first-served basis when capacity opens. Solar Rewards enrollment can be submitted simultaneously with the interconnection application.

Minnesota Net Metering

Minnesota PUC mandates net metering for all utilities under Minnesota Statute 216B.164:

Parameter	Details
Eligible size	Residential: 40 kW; Commercial: 1 MW
Credit rate	Full retail rate
Monthly carryover	Yes
Annual excess	Compensated at retail rate (favorable)
Utilities covered	All (investor-owned, municipal, cooperative)

Minnesota’s annual excess treatment is one of the most favorable in the US — unused credits at year-end are paid out at the retail rate, not forfeited or paid at avoided cost.

Made in Minnesota Solar Incentive

The Made in Minnesota (MiM) program provides additional per-kWh incentive for systems using qualifying Minnesota-manufactured solar modules:

Higher incentive rates than standard Solar Rewards
Requires modules manufactured in Minnesota or by MN-headquartered companies
Program administered by MN Department of Commerce
Limited annual capacity — check current enrollment status

Qualifying equipment: Modules made by companies with manufacturing facilities in Minnesota. The list of qualifying manufacturers changes — contact MNDOC for current qualifying products.

Local AHJ Requirements

City of Minneapolis

Building permit required from Minneapolis Building Services
Electrical permit required (City of Minneapolis Electrical Inspections)
Combination permit available for residential solar
SolarAPP+ accepted for qualifying residential systems

City of Saint Paul

Department of Safety and Inspections
Building and electrical permits required
SolarAPP+ participation — confirm current status

Dakota/Hennepin/Ramsey Counties

County building departments serve unincorporated areas
Permit processes vary by county

Ice and Snow Load Considerations

Minnesota’s significant snow load (roof design snow loads of 40–50 psf in Minneapolis area) affects racking structural design. Solar racking must be rated for the applicable roof snow load plus the panel weight. Roof structural review by a licensed engineer may be required for older homes — especially those with modifications or pre-existing load concerns. The structural assessment is separate from the electrical NEC compliance review.

Automate Minnesota Solar Compliance

SurgePV calculates NEC 690.7 string voltage for Minneapolis’s -31°C design minimum, generates NEC 2020-compliant permit packages, and exports Xcel Energy interconnection documentation.

Book a Demo

No commitment required · 20 minutes · Live project walkthrough

Frequently Asked Questions

What NEC edition does Minnesota use?

NEC 2020. Cold-climate string voltage calculation is particularly important for Minneapolis (T_min = -31°C) — the same module that allows 13 strings in California may only allow 11 in Minneapolis due to cold-temperature Voc correction.

How does Xcel Solar Rewards work?

Solar Rewards is a performance-based incentive — Xcel pays a per-kWh rate for all solar production. This is separate from and in addition to net metering credits. The program has waitlists; enroll early. Current rates vary by enrollment year — check Xcel’s website.

What is Minnesota’s annual net metering treatment?

Minnesota is favorable: annual excess credits are compensated at the full retail rate. This differs from states that forfeit unused credits (Washington) or pay only the avoided cost rate (many other states).